Pump Cell Electrode Coexistence Region Width Gradient
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Solution Overview
Problem
Conventional sensors exhibit low responsiveness to changes in voltage and current due to uneven quality alteration of the first electrode, leading to inefficient oxygen pumping between the measurement and reference chambers.
Innovation Solution
The sensor design includes a pump cell with a porous first electrode containing noble metal and ceramic material, where the surface is divided into regions with varying degrees of coexistence region expansion, enhancing the electrode's activity and responsiveness by differential temperature treatment during rich aging, ensuring higher activity near the reference cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rich aging treatment is performed uniformly on the first electrode, then the electrode activity is enhanced, but the quality alteration becomes uneven causing low responsiveness
Solution Approach 1:
The patent applies local quality by creating different coexistence region widths at different locations on the first electrode surface. The coexistence region width is controlled to be greater in the A region (farther from the third electrode) and smaller in the B region (closer to the third electrode). This spatial variation in electrode structure creates different oxygen pumping activities in different regions, improving the overall responsiveness to voltage changes while maintaining high electrode activity through the enriched coexistence regions.
2Reliability
If the coexistence region is expanded to enhance reactivity, then electrode activity increases, but the oxygen pumping becomes concentrated in one area reducing overall efficiency
Solution Approach 1:
The patent segments the first electrode surface into different regions (A region and B region) with different coexistence region characteristics. The A region has a greater coexistence region width for high reactivity, while the B region has a smaller coexistence region width. This segmentation distributes the oxygen pumping function across different electrode regions, preventing concentration in a single area and improving overall pumping efficiency while maintaining high reactivity in the A region.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design results in a pump cell with increased responsiveness to changes in voltage and current, effectively pumping oxygen between the measurement and external spaces, improving the sensor's overall performance.
Implementation Method 1
The pump cell includes a pump cell solid electrolyte body containing a ceramic material, a porous pump cell first electrode formed on the pump cell solid electrolyte body and exposed to the measurement chamber, and a pump cell second electrode formed on the pump cell solid electrolyte body and exposed to the element external space
Implementation Method 2
a reference cell which generates voltage Vs or current in accordance with the difference in oxygen concentration between the measurement chamber and a reference space which holds an atmosphere having a predetermined oxygen concentration
Implementation Method 3
Rich aging treatment is performed for the first electrode. As a result of the rich aging treatment, the quality alteration of the first electrode progresses, which results in formation of a coexistence region in which the noble metal and the ceramic material coexist. When such a coexistence region is formed, the area of the three-phase interface between the noble metal, the solid electrolyte, and the gas increases. Therefore, the reactivity between the first electrode and the gas is enhanced
Data Source
AI summary
A sensor includes a pump cell and a reference cell generating voltage Vs or current. The pump cell includes a pump cell first electrode and a pump cell second electrode. The surface of the pump cell first electrode includes a noble metal region formed of a noble metal, a ceramic region, and a coexistence region in which the noble metal and the ceramic material coexist. The width of the coexistence region in an A region of the surface of the pump cell first electrode is greater than the width of the coexistence region in a B region of the surface. The A region is a region close to the reference cell first electrode, and the B region is a region located further away from the reference cell first electrode as compared with the A region.